This invention concerns a method for detecting substances (generally proteins) which are capable of acting as antigens or antibodies in blood plasma or serum samples. More particularly the invention is concerned with a method for detecting hepatitis associated antigens and antibodies. The invention uses radioimmunoassay (RIA) or radioimmunological techniques which are well known in the art. These techniques can be used for detecting the presence of a particular substance, e.g. antigen or antibody, by attaching a radioactive material or other marker to a specific antibody and then measuring the amount of such labeled antibody which binds or attaches to a solid phase antigen. In the case of radioactively labeled antibody, by measuring the amount of radioactive emissions from the unknown sample and comparing them with standard curves obtained using known amounts of antigen it is possible to determine if a plasma or serum sample contains a particular antigen or antibody.
Many RIA prior art techniques employed to detect the presence of antigens or antibodies, including hepatitis associated antigens and antibodies, first immobilize the antibody by attaching it to a solid phase or substrate. Examples of these techniques are described in the following references: U.S. Pat. No. 3,646,346 issued to Kevin J. Catt on Feb. 29, 1972; an article entitled "A Solid-Phase Radioimmunoassay for a Thermostable Adrenal-Specific Antigen" by I. O. Auer, Y. Yagi, R. Kasukawa and F. Milgrom (Int. Arch. Allergy, Vol. 42, pages 816-825, received for publication January 15, 1972); and an article entitled "Prevalence of Hepatitis B Virus Antigen as Revealed by Direct Radioimmune Assay with .sup.125 I-Antibody" by C. M. Ling and L. R. Overby, (The Journal of Immunology, Vol. 109, No. 4, October 1972, pages 834-841.
In contrast to the above art, in the invention described herein, the antigen is bound to the solid phase components. Prior art which describes similar techniques is described in articles entitled "Rapid Micro-Radioimmunoassay for the Measurement of Antiviral Antibody" by Joel D. Rosenthal, Kozaburo Hayashi and Abner Louis Notkins (The Journal of Immunology, Vol. 109, No. 1, pages 171-173, July, 1972); "Detection of Antibody to Hepatitis-Associated Antigen in Hemophilia Patients and in Voluntary Blood Donors" by M. R. Peterson, L. F. Barker and D. S. Schade (Vox Sanguinis, Vol. 24, pages 66-75, received for publication March, 1972) and an article entitled "`Sandwich` Solid Phase Radioimmunoassay for the Quantitative Determination of Human Immunoglobulins" by Sydney E. Salmon, Gail Mackey and H. Hugh Fudenberg (The Journal of Immunology, Vol. 103, No. 1, pages 129-137, July 1969; received for publication Nov. 25, 1968). Both of these techniques will detect only antigen or antibody, not both, and differ from the technique described here in other particulars.